The present grant application deals with the determination of the primary structure of thin filament proteins from skeletal muscle. The first protein to be studied will be tropomyosin in all of its polymorphic forms, the number and character of which are presently under study by the applicant. Following this, attention will be directed to the troponins I and T (the sequence of human troponin C has already been established by the principal investigator). The data derived will form the basis for future investigations by which the corresponding proteins from dystrophic human muscle can be assessed for sequence alterations which may define the molecular basis of these diseases. Similarly, the sequence information will be invaluble to researchers involved in establishing normal physiological and biochemical parameters for these proteins. The isolation and purification of these proteins will include procedures such as ammomium sulfate and isoelectric fractionation, gel filtration and ion-exchange chromatography. Sequence analyses will make use of peptide mapping, automated amino acid analysis, automated peptide sequencing and gas chromatography.